Magnetic sandpaper holder



Patented Apr. 11, 1950 MAGNETIC SANDPAPER HOLDER Lewis Hopps, Darien, Conn., and Philip A. Smith, Pelham Manor, N. Y., assignors to The Indiana Steel Products Company, Chicago, 111., a corporation of Illinois Application September 14, 1948, Serial No. 49,244

6 Claims.

This invention relates to a sandpaper holder and method whereby sandpaper may easily be held in place in a holder. More specifically, this invention relates to a method and apparatus whereby sandpaper is held in place in a holder by means of magnetic attraction between two metal pieces. I

It is an object of this invention to provide a holder for sandpaper in which magnetic attraction is used to maintain the sandpaper in place.

Another object is to provide an easily fabricated metal holder for sandpaper.

A further object is to provide a method whereby sandpaper may be held in place in a metal holder by means of a permanent magnet.

In accordance with the general features of this invention, there is provided a permanent magnet, a shunt piece for this magnet, the bottom of which serves as a backing for sandpaper, and flat engaging surfaces between the magnet and the shunt piece whereby a clamping pressure may be maintained on the edges of sandpaper folded around the shunt piece and between the engaging surfaces of the magnet and shunt.

Other objects and features of this invention will more fully appear from the following detailed description taken in connection with the accompanying drawings which illustrate a single embodiment thereof and in which:

Figure 1 is a top plan View of the sandpaper ."Lf

holder;

Figure 2 is a sectional view taken along the line IIII of Figure 1;

Figure 3 is a front elevational view of the holder; and

Figure 4 is a sectional view taken along the line IV-IV of Fig. 1, showing a piece of sandpaper in position with marginal portions clamped between the pole pieces and shunt plate.

As shown on the drawings:

In the accompanying drawings reference numeral l0 designates a permanent magnet composed of a magnetic material such as iron or other ferromagnetic alloy. The magnet I0 is preferably square or rectangular in area. Opposite sides of the magnet I6 constitute poles H as shown in Figures 1, 3 and 4.

A pair of pole pieces M are connected to the poles ll of the magnet It as by soldering. The pole pieces 14 are in the shape of angle irons with sides 15 and IS. The edge of the side 15 of each of pole pieces I4 coincides with a surface of the magnet I0 and the magnet and pole pieces thereby cooperate to form a grip for easy handling. The pole pieces [4 are composed of a soft magnetic material such as soft steel and consequently the structure comprising the magnet Ill and the angle irons 14 may be considered as a horseshoe magnet with the outward flaringportions 16 serving as poles.

The surfaces of the sides I6 of the pole pieces I4 facing away from the magnet HI are disposed to engage a flat surface-on a plate l'l through a layer of sandpaper. The plate [1 serves as a shunt to provide a path of low reluctance for the magnetic flux between the pole pieces i4. Opposite sides of the plate i! have portions l8 which are turned slightly in the same direction. The plate I7 is preferably square or rectangular in shape and has margins extending a short distance beyond the limits of the sides It of the pole pieces [4 as shown particularly in Figure 1. The

'magnetic attraction existing between the members l6 and the plate ll is utilized to maintain sandpaper firmly in plate. As illustrated in Figure 4, a piece of sandpaper I9 is placed against the lower surface of the shunt plate ll, with its marginal portions, as at 2 i turned up and around the upturned portions Q8 of the plate H, to give a large surface area for the application of the clamping action between the members l6 and the plate H.

In order to prevent relative lateral movement between the members It and the plate H a series of bosses l2 are struck up in the plate ll by means of force applied, as by a punch, to the undersurface of the plate H. The bosses I2 coopcrate with the turned up section l8 of the plate ii to hold the magnet and angle iron assembly in place.

To place sandpaper in the holder it is only nee essary to separate th magnet assembly from the plate ll by force, wra the sandpaper around the plate H, as illustrated in Figure 4, and replace the magnet assembly in order to hold the sandpaper in place by means of magnetic attraction.

Since the force acting upon the sandpaper is entirely dependent upon the strength of the magnet it is important that a magnetic material of high permeability and magnetic strength be used in the magnet H). A suitable type of magnet is the so called Alnico magnet composed of an alloy of aluminum, nickel, cobalt, and iron. Alnico magnets of varying compositions as to alloying ingredients are well known in the art.

It will be noted that the pole pieces l4 and the magnet l0 combine to form an assembly which may be easily held by the hand. While the length alon the handle formed by the pole pieces [4 and the magnet I0 is normally about th width of the hand, it may be seen that a wider or nar rower magnet and pole piece assembly may be used. It will, of course, be understood that various other details of construction may be varied through a wide range without departing from the principles of this invention, and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

We claim as our invention:

1. A sandpaper holder comprising a thick permanent magnet the yoke of which is shaped to provide an easy hand grip, a shunt for the poles of said magnet consisting of a flat plate composed of a magnetic material, said plate having margins extending slightly beyond the limits of the magnetic poles, and bosses spaced at intervals along the margins of said plate to prevent slippage between said magnet and said plate, said magnet and said plate cooperatin to maintain in place sandpaper wrapped around said plate.

2. A sandpaper holder comprising a permanent magnet, pole pieces for said magnet, said pole pieces being composed of angle irons one edge of which is permanently attached to said magnet, the other edges of both angle irons flaring outward from said magnet, said magnet and angle irons cooperating to form a hand grip, a shunt for said pole pieces consisting of a plate of magnetic material having margins extending slightly beyond the flared edges of said angle irons and bent in the same direction outside of said angle irons, and bosses extending in the direction of the bent edges from the ends of said plate, said bosses and bent edges of said plate preventing relative movement between said plate and said pole pieces.

3. A sandpaper holder comprising a pair of angle irons of equal length, a permanent magnet with poles substantially the length of said angle irons, each pole of said magnet being permanently attached to one of said angle irons along one edge thereof, said angle irons being disposed with the edges not attached to said magnet poles to extend outward from said magnet in order to allow said angle irons to serve as pole pieces, a shunt for said pole pieces consisting of a plate of magnetic material having margins extending slightly beyond the flared edges of said angle irons and bent toward the magnet outside of said angle irons, and bosses extending toward the magnet from the ends of said plate, said bosses and turned sides of said plate preventing relative movement between said plate and said pole pieces.

4. A sandpaper holder comprising a permanent magnet, said magnet being composed of an alloy containing aluminum, cobalt, nickel and iron commonly known as Alnico, pole pieces for said magnet, said pole pieces being composed of angle iron one edge of which is permanently attached to said magnet, the other edges of both angle irons being turned outward from said magnet, said magnet and angle irons cooperating to form a hand grip, a shunt for said pole pieces consisting of a plate of magnetic material having margins extending slightly beyond the turned outward edges of said angle irons and bent toward said angle irons, and bosses extending toward said magnet from the ends of said plate, said bosses and turned sides of said plate preventing relative movement between said plate and said pole pieces.

5. A holder for non-magnetic sheet material comprising a permanent magnet assembly including pole pieces providing spaced surfaces and a shunt plate of soft magnetic material serving as a backing for said non-magnetic material and having surfaces conforming to said spaced pole surfaces, said plate and pole pieces having portions outside of said surfaces cooperating with each other to prevent relative surface movement therebetween without separation of said surfaces, whereby said non-magnetic material may be positioned on said shunt plate as a backing with portions of said material extending between said conforming surfaces and held in position by the magnetic attraction of said magnet assembly for said shunt plate.

6. A holder for non-magnetic abrasive sheet material comprising a permanent magnet having outwardly flaring poles providing spaced surfaces, a plate shunted across said poles having conformin surfaces, and a plurality of spaced protuberances formed on said plate cooperating with adjacent portions of the poles of said magnet to prevent any substantial relativ movement of said conforming surfaces over each other, said plate being adapted to serve as a backing for said non-magnetic abrasive sheet material and to hold the sheet material in place between said conforming surfaces by the clamping pressure provided by the magnetic attraction between said plate and said poles, and said protuberances serving to prevent relative shifting movement of said plate and said pole pieces during relative movement of the holder over a surface to be abraded.

LEWIS HOPPS. PHILIP A. SMITH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 93,931 Westcott Aug. 17, 1869 809,615 Hopkins Jan. 9, 1906 840,982 Williams Jan. 8, 1907 1,137,492 Kidney Apr. 27, 1915 1,501,192 Severns July 15, 1924 FOREIGN PATENTS Number Country Date 544,110 Great Britain Mar. 2'7, 1942 

